We investigate the quantum correlations of a two-qubit XYZ Heisenberg spin-1/2 chain model with Dzyaloshinskii–Moriya interaction. The two-qubit system is considered in thermal equilibrium. The variations of logarithmic negativity, uncertainty-induced quantum nonlocality (UIN) and trace distance discord, versus the parameters characterizing the system, are analyzed. The results show that the UIN measure captures quantum correlations that cannot be revealed by entanglement and trace discord. We also show that the Dzyaloshinskii–Moriya interaction enhances the non-classical correlations between the spins and can weaken the undesirable destructive effects of thermal fluctuations. In addition, an entangled–unentangled phase transition can be detected from the behavior of logarithmic negativity.
Abstract The thermal quantum correlations in a two-qubit one-dimensional XXZ Heisenberg spin- 1 2 chain subjected to an inhomogeneous magnetic field are investigated. The concurrence, as thermal entanglement quantifier, and the discord-like quantifiers, namely the trace distance discord and local quantum uncertainty, are computed. Their dependence on the anisotropy parameter γ , uniform magnetic field B , coupling constant J and nonuniform magnetic field b are presented in detail. The mentioned quantifiers behaviors in terms of this parameters are compared and discussed. The results show that TDD is always much stronger than the concurrence and LQU, whereas the latter two show a swinging behavior depending on system parameters. Also, we have shown that the nonuniform magnetic field can reduce the effects of temperature on thermal correlations. Furthermore, the thermal correlations, for fixed values of b , can be enhanced in the antiferromagnetic system in comparison to the ferromagnetic one. In addition, the quantum correlations amounts in the ferromagnetic system are deteriorated when γ decreases, but they are improved when the system is antiferromagnetic.
Abstract The thermal quantum correlations’ dynamics of an anisotropic two-qubit Heisenberg XYZ model in the presence of a x-projection external magnetic field are investigated in this paper. We use local quantum-Fisher information (LQFI), and log-negativity, and local quantum-uncertainty (LQU) to analyze the generated quantum correlation dynamics. Using the associated parameters, we demonstrate the successful generation of entanglement and quantum correlations beyond entanglement in the anisotropic spin-chain state. Certain values and ranges of anisotropy, external magnetic field, and spin coupling strength are proposed that can be used to achieve either a non-maximal or maximal quantum correlated state. The characterization of the spin-chain state by various parameters determines the dynamical patterns, degree, and preservation limits of the associated quantum correlations. Finally, the LQFI, LQU, and log-negativity functions’ robustness is highly dependent on their parameters, and they rarely agree on the degree of quantum correlations and dynamical patterns.
We investigate the effect of Calogero-Moser (CM) type interactions on the thermal entanglement and teleportation in an anisotropic two-qubit Heisenberg XYZ system with Dzyaloshinskii-Moriya (Dz) interaction in the presence of the external magnetic field. In this regard, the system is designed and analytically solved. The final state density of the system is obtained, and the impact of the system parameters is investigated. The negativity is used to quantify the entanglement dynamics over the system. The generated entangled channels are examined to exchange the information between the system qubits using the standard teleportation protocol; then, the fidelity of the transmitted information is quantified. The effect of the system parameters (Dzyaloshinskii-Moriya, Spin-orbit coupling, CM type interaction, and magnetic field) in the dynamics of the entanglement and state transfer is investigated. Our results indicate that the strength coupling, Dzyaloshinskii-Moriya (Dz) interaction, and magnetic field have a great effect on the dynamics of the entanglement and, consequently, the quality of the generated channels to exchange the information. In addition, we observe that the entanglement of sudden death exists when the distance between the spins is increased.
We study thermal quantum correlations and coherence in Heisenberg
XY model with anisotropic interactions under a uniform magnetic field $ B $. Using concurrence
C, local quantum uncertainty (LQU), Bell-Clauser-Horne-Shimony-Holt (CHSH) nonlocality $ \mathbb{B}$, and coherence
Cl as quantifiers, we analyze how magnetic anisotropy $ δ_m $, coupling anisotropy $ δ_c $, Dzyaloshinskii-Moriya (DM) interaction $ D $, temperature $ T $, and magnetic field $ B $ modulate quantum resources. At low temperatures and relevant magnetic fields, the entanglement is maximized, but exhibits sudden death for $ δ_m = 0 $, which turns into a smooth decay as $ δ_m $ increases, highlighting its stabilizing role. LQU shows that stronger anisotropy suppresses quantum correlations, while $ \mathbb{B} $ induces a non-monotonic response peaking at a critical field $ B_c
.Bell−CHSHnonlocalityviolations( \mathbb{B} > 2 $) persist below $ B_c
,butthermalnoise( T \geq 1 $) suppresses them. Coherence $ C_l $ is most robust to thermal fluctuations, especially for high
δm, which also dampens abrupt quantum phase transitions. The DM interaction is essential for entanglement generation, with $ D $ and anisotropy synergistically enhancing correlation resilience. We identify a hierarchy of thermal degradation: nonlocality ($ \mathbb{B}
)vanishesfirst,followedbyentanglement( C $), then general quantum correlations (LQU), while coherence $ C_l $ persists the longest. These results demonstrate tunable control of quantum resources via anisotropy and external parameters, providing insights for the design of robust spin-based quantum technologies.
Abstract We employ entanglement negativity, local quantum uncertainty (LQU), and local quantum Fisher information (LQFI) to characterize thermal entanglement between two XYZ-Heisenberg-qubit states under the influence of Dzyaloshinsky-Moriya(DM) and Kaplan-Shekhtman-Entin-Wohlman-Aharony (KSEA) interactions, as well as a magnetic field and thermal equilibrium temperature. A comparative examination reveals similar behaviors among these correlation measures. For the antiferromagnetic scenario, we observe that increasing the DM interaction parameter D z enhances thermal entanglement. Conversely, in the ferromagnetic case, the behavior of thermal entanglement differs with varying D z . Additionally, employing Kraus operators, we explore the performance of these quantifiers under decoherence. Notably, LQFI exhibits greater robustness than negativity and LQU, even displaying a frozen phenomenon at some time under dephasing effects.